The present invention relates to a high-frequency incision instrument for an endoscope.
A high-frequency incision instrument for an endoscope is inserted through an instrument insertion channel of the endoscope for incising a mucous membrane or another part of a human body when put to use, and is generally configured to project forward and retreat, through a forward end portion of a flexible over tube, a rod electrode disposed close thereto by remote operation from an operating unit connected to a proximal side of the over tube.
In such operation, the incision depth of the mucous membrane or another part varies depending on the state of the affected part to be incised, the environment of use of the high-frequency incision instrument and so forth. Accordingly, some high-frequency incision instruments are configured such that a maximum projection length of the rod electrode from the forward end portion of the over tube can be adjusted as desired, thereby enabling incising the affected part to a safe and optimal depth, for example as disclosed in Japanese Patent Provisional Publication No. 2002-113016 (hereinafter, referred to as '016 publication).
The high-frequency incision instrument according to '016 publication includes a pair of stoppers respectively disposed at a forward end portion of the over tube and a proximal end portion of the rod electrode so as to be butted to each other to thereby determine a maximum projection length of the rod electrode from the forward end portion of the over tube, and the control of the maximum projection length of the rod electrode is executed by adjusting a position of a forward mouthpiece screw-fitted on the forward end portion of the over tube.
However, the forward end portion of the over tube where the rod electrode is disposed is inserted into the body through the instrument insertion channel of the endoscope when the high-frequency incision instrument is in actual use. Accordingly, for adjusting the maximum projection length of the rod electrode in accordance with the state of the affected part, the high-frequency incision instrument has to be drawn out once through the instrument insertion channel, which often leads to troubles such as repeated adjustment procedures and losing track of the affected part.
To alleviate such troubles, it might be an option to provide a variable stopper that controls the maximum projection length of the rod electrode on the operating unit close to the operator, however when the high-frequency incision instrument is inserted through the endoscope which is serpentinely inserted in the body, the adjustment of the stopper performed on the proximal side is not correctly reflected in the resulting projection length of the rod electrode from the forward end portion of the over tube. Providing the stopper at a proximal position, therefore, is not effective in accurately adjusting the maximum projection length of the rod electrode.